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Geometric Facts about The Mahoujin
Mahoujin In Ep. 48 and Ep. 50, there is a "Magic Circle" shown in Akazukin Chacha, as Seravi said, it's called "Mahoujin" in Japanese . Mahoujin and number "7" hetptaa.jpg Jinn1-0.jpg As we can see, there are "7" small circles on the rim of main circle, these small circles form a regular heptagon. And as this pic has shown, if we draw an externally tangent square on the "inner" circle, then the four vertices of that square just touch the "Main" circle. That's said, the radius ratio of the main circle to the inner circle is: 1:\dfrac {1} {\sqrt {2}} . And, if we make externally tangent circle on the yellow heptagram (not its white rim), than the ratio of this circle to the main circle is 0.624 : 1, aka: \cos \left( \dfrac {360} {7}\right) :1 that means if we make an (wider) heptagram (radius = 1) like this pic: then the radius of its inscribed circle of the inner heptagon is 0.624 that's said, if we make tangent lines on every vertex of the yellow heptagram, then those lines can form a wider heptagram, and this new heptagram's every vertex touch the main circle. We call the externally tangent circle of the yellow heptagram "P circle". Now we calculate the ratio between "inner circle" and "P circle", we find it is: 1:\sqrt {2}\times \cos \left( \dfrac {360} {7}\right) = 1: 0.8817~, then 2 \times \arccos \left( 0.8817 \cdots \right) = 56.29216~ and approximately:(accuracy = 99.933%): 56.29216~ \approx \arctan \left( \dfrac {3} {2}\right) thus, based on the inner circle, we can make both "main circle" and "P circle" using ruler and compass, like this pic: and if we make a tangent line S on the P circle, then it's a nearly perfect heptagon approximation. (the two points where S cross the main circles is 2*(360/7)) As far as I know, there's no document in the world( realworld ) had recorded this approximation method. 　　　　　　　　　　　　　　　 An interesting thing is, let the hypotenuse be sqrt(ln(180/7)), then that (original) 3/2 will be 1.4990~. The accuracy of this is even higher then that commonly used atan(79/63) ( also (9^2-2)/(8^2-1) ). Although Natural logarithm ''does not relate to ruler-compass, it can build a link between 180/7 (number) and 360/7 (degree) via our method. Akazukin Chacha does have a lot of delicate properties like this. As we can see the thing above, that is the proof of that" 1:\dfrac {1} {\sqrt {2}} " ratio dose relate to the "7" or "heptagon". Now, if we calculate the area of the 7 small circles and the inner circle, then the area of the small circles is: radius of small circles = \dfrac {\sqrt {2}-1} {2\sqrt {2}}= t thus the area is t^{2} *pi, approximately \dfrac {3} {140}\pi (''Continued fraction about ''1/(23+1/3) ;accuracy = 99.916%) and the area of the inner circle is 0.5 or 1/2, and the area between every small circles (as the pic's blue area) is (((1-0.5)/7)-(3/140))*pi = 7pi/140.= pi/20. therefore, if we let the area of "Main circle" = 140pi, then the simple integer ratio of inner circle : small circle : left area (blue area) is = 70 : 3 : 7 (accuracy = 99.916%) Again, that is the proof of the area's ratio is related to "7". The Central Multi-fold circles and the Coins The pic above is the outline-drown Mahoujin, which had shown in the end of Ep. 48. The biggest blue circle relates to the yellow heptagram's white rim, let the radius of '''inner circle' be 1, then the ratio of the inner circle to the biggest blue circle is 1 : 0.356895867~ (sin(360/7*4)/cos(360/7)). The second blue circle: If we set the area of the small circles (on the rim of the main circle, with its white rim) to 4000 cm^2,then this second-blue-circle's '''area is equal to 10000 cm^2, in another word 2.5 times of the small circle with their rim. If we set the radius of inner circle to R, then the ratio between inner - '''second-blue-circle is: R : \dfrac {\sqrt {10} - \sqrt {5}} {2\sqrt {2}} R The third blue circle, if we set the diameter of the inner circle to ''365.242199 '' (beware of this value), then the radius of this third-blue-circle is 56.433~ (1/2 Chacha's height). You can test those relations yourself on this pic (original size), the length of pixels in this pic is 19 times of its real length The pixel length in the pic is: For more about these numeric-game-ish things shown in Akazukin Chacha, please see another article, Characters' heights, Unit Ma and Unit CM in Akazukin Chacha. Now we regard the (shade of?) coin on the center, we can see it's from the 4-fold-circle formation 'whose radius is half of the '''third-blue-circle. ' And in this pic, we can see the height of the coin is 1 / 32 times of Magical Princess' height (the ratio of Chacha to MP is 1 : 1.618~, aka "Golden ratio", as the pic shown), As we know MP's height is equal to the radius of the 'inner circle '''of Mahoujin, that's said the "shade" of the coin on the first pic is 4 times bigger than real coins (by area). So we have drawn the 1 / 4-radius-of-'''third-blue-circle '''formation on the first pic. As we can see by the plot, Magical Princess plays the "ideal human" or "the Eidos / Idea of human" role in Akazukin Chacha. All features of MP are meaningful, because they relate to almost all other things shown in Akazukin Chacha. The white rim of small circles We can see the radius ratio between the outer-white-rim and inner-white-rim of small circles is about 1 : cos(pi/6). And we have seen above that Chacha : MP = 1 : 1.618~ (''golden ratio) So, let the radius of inner circle be 1, then Chacha's height is (sqrt(5)-1)/2. The diameter of the central circle is 2*(cos(3pi/7)/cos(2pi/7)), or 0.713791735 We can see 0.618(Chacha's height)/(0.713791735) is almost cos(pi/6), in the other word, the "white rim ratio" of small circles. We can see the "central circle" and the small circles actually have same mode. Thus, let the (big) inner circle's diameter be 1, the diameter of the "inner circle" of small circles is: \dfrac {\cos\dfrac {2\pi } {7}\left( \sqrt {5}-1\right) \left( \sqrt {2}-1\right) } {8\cos \dfrac {3\pi } {7}} this can be roughly: ((sqrt(2)-1)/2)*cos30 (hexagon), accuracy 99.9793%. That's said the "Golden ratio" can be: \dfrac {\cos \dfrac {2\pi } {7}} {2\cdot \cos \dfrac {3\pi } {7}\cos \dfrac {\pi } {6}}\approx \phi (accuracy: 99.9793%) We can make another approximation as: \dfrac {\cos \dfrac {2\pi } {7}} {\cos \dfrac {3\pi } {7}}\left( \dfrac {2} {5}\right) ^{3} (accuracy: 99.99924224%) That's said the '''inner circles of small circles '''and the '''inner circle of the MAIN circle '''are actually related, as the pic: If we make an (outer) heptagram based on the (main) inner circle, we can see its diameter is almost '''2 times of the (main) outer circle. We know the diameter of the "Mahoujin Garden" (see below) is 5 times of the (main) outer circle, this is another 2/5 ratio. Thus the diameter of small inner circles can be written as: diam. Mahoujin Garden* \left( \dfrac {2} {5}\right) ^{4} (accuracy 99.48%) The pic above shows Chacha's height as the Diam. of third Central circle, ' and MP as the radius of the (inner) main circle. There is also a '''Triple-in-One '''relation has been shown: The third central circle is 3 times bigger then the small circles' inner circle ( by area ). (since cos(3pi/7)*2/cos(2pi/7)*(sqrt(2)-1) is about sqrt(3) (99.5%)) White rim of the Main Circle & the secondary heptagram As the pic, we can see the white rim of the outer circle is: (57/55)*original outer circle (expanded) We assume the white rim of the inner circle to be this ratio as well, so the inner white rim can be: (55/57)*original inner circle (contracted) since it has: \dfrac {1+\sqrt {1+8\sqrt {8}}} {2\sqrt {8}}\approx \dfrac {57} {55} so (outer circle's diameter)*57/55 - ( inner circle's diameter )*55/57 is approx to the radius of the inner circle. ((outer circle's diameter)*57/55 - ( inner circle's diameter )*55/57 is two times of the space between expanded outer circle and the contracted inner circle) It also means that: If we split the white ring to '''56 parts, ' let the length between two sides of the white rim be a, then the area of each parts is (a^2)*pi Properties relate to this 57/55 ratio # 57/55 is also approximately 1/cos(2pi/'''24). That's said a Dodecagon '''around the inner/outer circle, formed by the angles from '24 coins '''formation ( see below ), can make the white rims of the Outer / Inner.. # The radius of inner circles about 153^(1/4) times of the width of each white rim/56. The (153^(1/4))^2 or 12.369~ is close the the ''annual lunation rate. The properties below belong to the 1st Central circle and its expanded white rim. # The quarter of rim is close the the diam. of ''expanded white rim of 1st Central circle, ''which is also about (57/55)*1st Central circle. # The bottom two vertices of the yellow (approximately) triangle on each arm of the yellow heptagram forms a 38.5714~ or 90-(360/7) angle when they linked to the center point of whole Mahoujin. The properties below belong to the ''Unit MA and Unit cm ''article and its of inner = 365.2421990741MA result. # The whole area of rim can be set to '''20 sq. meters, thus the accurate value of 57/55 is : 9*400*sqrt(5pi)/13770.07731. Center of mass of Circular sectors on the whole Mahoujin As the pic shows, the mass centers of continuous Circular Sectors ( on a circle ) forms a Cardioid. Regard this Cardioid ''as a "heart" (shape), then we can get that the length between the two sides of the "heart" is almost equal to 'main inner circle/sqrt(2).' It just like the outer circle is made by main inner circle*sqrt(2). That's said the square of "heart" -> inner -> outer is a series ascending by 1.4142~ or sqrt(2). Additionally, we have this: '(cos0+cos45-cos30)*R=(57/55)*(2/3+0.1448224188)*R''' (be accurate when 100.0099403% of 57) R is the radius of the outer, the (2/3+0.1448224188) multiplier is height (rate) of of the "heart". That's said the "hearts" shape also relates to outer's inscribed square '''and hexagon.' Now see into the bottom point of "heart" and that (55/57)*inner circle, where marked by red.dashed lines. We know the distance from central point to the bottom of "heart" is (2/3)*(57/55)*sqrt(2)*of main inner. Thus the length inside inner's white rim is '{1-(2/3)*(57/55)*sqrt(2)}*of main inner.' This length is close to ((1-55/57)/φ)*of main inner. (be accurate when 100.0777% of 57) We use this relation to build the ''expanded white rim of 1st Central circle: Align MP's top to the top of the inner, align Chacha's top to the 1/φ position from inner's white rim, then the distance between Chacha's standing ground to MP's standing ground, hence the distance (55/57)*height - height, is the radius of expanded white rim of 1st Central circle. E'xpanded white rim of 1st Central circle' The radius we make from MP-Chacha, is also close to the 1st central circle multiply with (57/55): (55/57)*(1-1/φ) = (57/55)*cos(3pi)/cos(2pi) approx. (be accurate when 99.823% of 57) The "Mahoujin Garden" and number "24" In Ep. 48, as we can see the "Garden" where the Mahoujin land, its radius is 5 times of the Mahoujin, as the pic: The number 5 is also relates to 7 via the inner / main circle relation. We can see: 5 \approx \dfrac {7} {\sqrt {2}} (98.995%) that's said if we draw 7 '''inner-circle-size circles (begin with the true inner circle ), than it reaches the rim of the Garden. thus the garden's area = 25*(mahoujin area). and the "meadow" area is (garden-1*Mahoujin) = 24 times of the Mahoujin's area. that's said, every fan-shaped area (as the pic, divided by red straight lines) is equal to a Mahoujin. Is "24" meaningful in Akazukin Chacha? As we can see, "Princess Medallion" has 24 "golden beans" around the gem. And the LCM of Medallion's gem (hexagon, 6) and Chacha's ring's gem (octagon, 8) is also 24. As we know, in Ep.5 or Ep, 22, the ring is the key to unlock the gem on Medallion. Meda.gif 0se22.png 0se23.png More importantly, the number "5" is the unique solution of patter on the left pic. We explain it below. At the beginning of Ep. 28, there was a "Map" had been shown: As the "Map" said, the 3 centers of each pond forms an equilateral triangle, and there is a big ( virtual ) circle wrap over all three circles. (The rim of the "big circle" touches every there ponds). If we use Chacha's height as a reference, than we can measure out the "three ponds" in Ep. 28, which every ponds radius is equal to Ep. 48's Mahoujin's diameter. And as the minimal distance between two ponds (the white line on the bottom of pic) says, the '''circular central space of these ponds is equal to a Mahoujin ( as the white space on the pattern on the top of the pic). That's said, the radius of the wrap circle 'of three ponds ('externally tangent circle of the three ponds) is 2*(2*r)+1 = 5r, and like a miracle, 5r is just the "Mahoujin Garden"'s radius in Ep. 48. Now we can draw the three ponds and its wrap circle geometrically, as the red-black-green pattern on the pic. We know the wrap circle's area is 25 r^2pi, and the "pond"'s area is (2*2)r^2pi = 4r^2pi, thus minus the three ponds and the central area (radius 1r), the residual area is: 25r^{2}\pi -1r^{2}\pi -3\cdot 4r^{2}\pi = 12r^{2}\pi Again, it's a miracle, the "12r^2pi" just equal to the sum of three pond's area, and we know the "residual area" is divided into 3 equal parts. That's said, every "pond" and the semi-fan-shaped area on its opaposite side, are equal. This is the unique solution in the case of "3" on this pattern, as we can proof it in math, like the pattern: If we want to make the blue circle and its opposite yellow area equal, then the central circle (red circle) to side circles (blue circle)'s radius ratio is 1 : 2, thus the wrap circle '''to central circle is 5 : 1, just like the one Ep. 28 or Ep.48's "Mahoujin Garden" has shown. ...editing... Also, the "coins" from Ep. 36 to 47, the angle of its two sides is 15 degree, therefore '''24 coins form a circle: ...editing... The formation of the 4-fold-circles is: * The diameter of 1 '''circle is about 4.9 times of the coin's height. * We can make '''4 circle with this relation. * The ratio of 1''' to '''3 '''is 1.4785752424~ * The ratio of '''4 to '2 '''is also 1.4785752424~ Let ANS=2*cos(pi/24), then ANS-1/ANS = 1.4785752424. This ratio can make the "opposite angle" equals to two times of the central angle when θ = 2pi/24. We can see more this "ANS-1/ANS" type formulas in the ''Unit MA and Unit CM article. Note: The coin picture from the OS (Official Setting) is not parallel to the screen surface, so we have applied fixes on it. ...editing... Category:Extras Category:By math